package cn.me.fdfs.util;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * @author zhanghf
 *
 */

public class DigestUtil {
  private static char[] base64EncodeChars =
      new char[] {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
          'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p',
          'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'};

  private static byte[] base64DecodeChars = new byte[] {-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
      -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62,
      -1, -1, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
      10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31,
      32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1};

  static char hexdigits[] = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};

  public static String getMd5Digest(String cleanText) {
    MessageDigest digest = null;
    try {
      digest = MessageDigest.getInstance("MD5");
    } catch (NoSuchAlgorithmException e) {
      // failed to load the MD5 algorithm
      return null;
    }

    byte[] hashBytes = null;
    try {

      digest.update(cleanText.getBytes());
      hashBytes = digest.digest();
    } catch (Exception e) {
      // failed to compute hash
      return null;
    }

    String result = encodeHex(hashBytes);

    return result;
  }

  public static String getMd5DigestFileByReadFile(String filePath) {
    MessageDigest digest = null;
    String str = "", data = "";

    try {
      digest = MessageDigest.getInstance("MD5");
    } catch (NoSuchAlgorithmException e) {
      // failed to load the MD5 algorithm
      return null;
    }

    byte[] hashBytes = null;
    try {
      BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(filePath)));
      while ((data = br.readLine()) != null) {
        str = str + data;

      }

      digest.update(str.getBytes());
      hashBytes = digest.digest();
    } catch (Exception e) {
      // failed to compute hash
      return null;
    }

    String result = encodeHex(hashBytes);

    return result;
  }

  /**
   * 对文件全文生成MD5摘要
   * 
   * @param file 要加密的文件
   * @return MD5摘要码
   */



  public static String getMd5DigestFile(String filePath) {


    FileInputStream fis = null;
    try {
      MessageDigest md = MessageDigest.getInstance("MD5");
      fis = new FileInputStream(new File(filePath));
      byte[] buffer = new byte[2048];
      int length = -1;
      long s = System.currentTimeMillis();
      while ((length = fis.read(buffer)) != -1) {
        md.update(buffer, 0, length);
      }
      byte[] b = md.digest();
      return byteToHexString(b);
      // 16位加密
      // return buf.toString().substring(8, 24);
    } catch (Exception ex) {
      ex.printStackTrace();
      return null;
    } finally {
      try {
        fis.close();
      } catch (IOException ex) {
        ex.printStackTrace();
      }
    }
  }

  /**
   * 把byte[]数组转换成十六进制字符串表示形式
   * 
   * @param tmp 要转换的byte[]
   * @return 十六进制字符串表示形式
   */
  private static String byteToHexString(byte[] tmp) {
    String s;
    // 用字节表示就是 16 个字节
    char str[] = new char[16 * 2]; // 每个字节用 16 进制表示的话，使用两个字符，
    // 所以表示成 16 进制需要 32 个字符
    int k = 0; // 表示转换结果中对应的字符位置
    for (int i = 0; i < 16; i++) { // 从第一个字节开始，对 MD5 的每一个字节
      // 转换成 16 进制字符的转换
      byte byte0 = tmp[i]; // 取第 i 个字节
      str[k++] = hexdigits[byte0 >>> 4 & 0xf]; // 取字节中高 4 位的数字转换,
      // >>> 为逻辑右移，将符号位一起右移
      str[k++] = hexdigits[byte0 & 0xf]; // 取字节中低 4 位的数字转换
    }
    s = new String(str); // 换后的结果转换为字符串
    return s;
  }

  private static String encodeHex(byte[] bytes) {
    StringBuffer hex = new StringBuffer(bytes.length * 2);

    for (int i = 0; i < bytes.length; i++) {
      if (((int) bytes[i] & 0xff) < 0x10) {
        hex.append("0");
      }
      hex.append(Integer.toString((int) bytes[i] & 0xff, 16));
    }

    return hex.toString().toUpperCase();
  }


  // ����
  public static String encode(byte[] data) {
    StringBuffer sb = new StringBuffer();
    int len = data.length;
    int i = 0;
    int b1, b2, b3;
    while (i < len) {
      b1 = data[i++] & 0xff;
      if (i == len) {
        sb.append(base64EncodeChars[b1 >>> 2]);
        sb.append(base64EncodeChars[(b1 & 0x3) << 4]);
        sb.append("==");
        break;
      }
      b2 = data[i++] & 0xff;
      if (i == len) {
        sb.append(base64EncodeChars[b1 >>> 2]);
        sb.append(base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]);
        sb.append(base64EncodeChars[(b2 & 0x0f) << 2]);
        sb.append("=");
        break;
      }
      b3 = data[i++] & 0xff;
      sb.append(base64EncodeChars[b1 >>> 2]);
      sb.append(base64EncodeChars[((b1 & 0x03) << 4) | ((b2 & 0xf0) >>> 4)]);
      sb.append(base64EncodeChars[((b2 & 0x0f) << 2) | ((b3 & 0xc0) >>> 6)]);
      sb.append(base64EncodeChars[b3 & 0x3f]);
    }
    return sb.toString();
  }

  // ����
  public static byte[] decode(String str) throws UnsupportedEncodingException {
    StringBuffer sb = new StringBuffer();
    byte[] data = str.getBytes("US-ASCII");
    int len = data.length;
    int i = 0;
    int b1, b2, b3, b4;
    while (i < len) {
      /* b1 */
      do {
        b1 = base64DecodeChars[data[i++]];
      } while (i < len && b1 == -1);
      if (b1 == -1)
        break;
      /* b2 */
      do {
        b2 = base64DecodeChars[data[i++]];
      } while (i < len && b2 == -1);
      if (b2 == -1)
        break;
      sb.append((char) ((b1 << 2) | ((b2 & 0x30) >>> 4)));
      /* b3 */
      do {
        b3 = data[i++];
        if (b3 == 61)
          return sb.toString().getBytes("iso8859-1");
        b3 = base64DecodeChars[b3];
      } while (i < len && b3 == -1);
      if (b3 == -1)
        break;
      sb.append((char) (((b2 & 0x0f) << 4) | ((b3 & 0x3c) >>> 2)));
      /* b4 */
      do {
        b4 = data[i++];
        if (b4 == 61)
          return sb.toString().getBytes("iso8859-1");
        b4 = base64DecodeChars[b4];
      } while (i < len && b4 == -1);
      if (b4 == -1)
        break;
      sb.append((char) (((b3 & 0x03) << 6) | b4));
    }
    return sb.toString().getBytes("iso8859-1");
  }


  public static void main(String[] args) {
    // TODO Auto-generated method stub
    String abc = getMd5DigestFile("d:/1.vx2");
    System.out.print(abc);

  }

}
